Astronomers find evidence of planets in debris disks after years of imaging

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Tom Esposito/Courtesy

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After about four years of imaging more than 100 young stars with advanced technology, astronomers released high-quality images of 26 debris disks June 15 with evidence of planets in almost all the disks.

According to Tom Esposito, a postdoctoral scholar in the astronomy department at UC Berkeley and the first author of the study, astronomers attached the Gemini Planet Imager, or GPI, to the Gemini South Telescope in Chile to find the debris disks. Made of tiny dust particles, seven of these disks were imaged for the first time.

“Our overall goal here is to kind of get a picture of what these young forming solar systems are like and be able to ask what kind of diversity is out there,” Esposito said.

Detecting faraway planets is extremely difficult, according to Esposito. The researchers looked instead for indirect evidence of planets existing. The disks will be used as a “proxy” to study the planets that may be nearby, according to Gaspard Duchêne, an associate researcher in the astronomy department at UC Berkeley and a co-author of the paper.

Twenty-five of the 26 imaged disks had an inner region that was free of dust. Esposito said this can be caused by planets orbiting in the region and collecting dust particles. Another indication of nearby planets in the survey was the presence of elliptical or asymmetric disk shapes.

“We would normally expect these disks to be mostly symmetric or circular unless there is some other perturbing force that is disturbing that, like the presence of a planet,” said Justin Hom, a graduate student at Arizona State University and a co-author of the paper.

The use of the 8-meter Gemini South Telescope was one factor in how this survey was able to attain such sharp images. A large telescope is crucial because it allows researchers to see smaller and fainter objects, Hom said.

Getting clear images was also due to the advanced GPI instrument, Esposito added. The GPI utilizes an adaptive optics system to remove atmospheric blur, as well as a coronagraph to block the light from nearby stars. Looking at the disks in polarized light was also important.

Esposito said detecting the polarized light helps clearly separate the light of the disk from the light of the star. Polarization can also help researchers discover what the dust rings are made of.

Because of the large number of disks found in this survey, comparisons can be drawn between planetary systems, Esposito said. This helps astronomers understand the origins of our solar system, according to Paul Kalas, an adjunct professor of astronomy at UC Berkeley and the second author of the paper.

“We’re really looking back in time. These stars are between 10 and 100 million years old,” Kalas said. “By studying them in detail and in such large numbers, we hope to understand our own solar system’s evolution.”

Contact Vani Suresh at [email protected] and follow her on Twitter at @vanisuresh_.